The low-mass population of the Rho Ophiuchi molecular cloud

TL;DR

This study identifies and confirms six new brown dwarfs in the Rho Ophiuchi molecular cloud using deep near-infrared imaging and spectroscopy, expanding knowledge of its low-mass population.

Contribution

First comprehensive near-IR survey of Rho Ophiuchi identifying new brown dwarfs and assessing their properties.

Findings

Confirmed six new brown dwarfs with spectral types M6.5 to M8.25

Identified 110 candidate members, 80 of which are new associations

Deep imaging reached completeness limits of ~20.5 mag in J

Abstract

Star formation theories are currently divergent regarding the fundamental physical processes that dominate the substellar regime. Observations of nearby young open clusters allow the brown dwarf (BD) population to be characterised down to the planetary mass regime, which ultimately must be accommodated by a successful theory. We hope to uncover the low-mass population of the Rho Ophiuchi molecular cloud and investigate the properties of the newly found brown dwarfs. We use near-IR deep images (reaching completeness limits of approximately 20.5 mag in J, and 18.9 mag in H and Ks) taken with the Wide Field IR Camera (WIRCam) at the Canada France Hawaii Telescope (CFHT) to identify candidate members of Rho Oph in the substellar regime. A spectroscopic follow-up of a small sample of the candidates allows us to assess their spectral type, and subsequently their temperature and membership. We select 110 candidate members of the Rho Ophiuchi molecular cloud, from which 80 have not previously been associated with the cloud. We observed a small sample of these and spectroscopically confirm six new brown dwarfs with spectral types ranging from M6.5 to M8.25.